Abstract Detail

Biotic and abiotic stress

Castellarin, Simone Diego [1], Wong, Darren C. J. [1], Savoi, Stefania [2], Miculan, Mara [3], Peterlunger, Enrico [4], Mattivi, Fulvio [2].

Large scale metabolite and transcript analysis revealed a complex modulation of berry secondary metabolism under severe water deficit in white grapes (Vitis vinifera L.).

The quality of wine-grapes (Vitis vinifera L.) is largely affected by the concentration of secondary metabolites in their tissues. Water deficit increases flavonoid biosynthesis in red grapes and this improves the quality of derived wines. The effect of severe water deficit on the accumulation of secondary metabolites in white grapes remains largely unknown. In this study we employed and combined transcriptomics and metabolomics to evaluate the impact of water deficit on berry secondary metabolism in the ‘Tocai Friulano’ white-grape variety. An open field experiment was conducted in north-eastern Italy in 2012. From fruit set to harvest irrigation was applied to control (C) vines in order to maintain stem water potential above -0.8 MPa, while it was withheld from deficit irrigated (D) vines unless when stem water potential decreased below -1.4 MPa. The effect of these treatments on the phenolic, carotenoid, VOC accumulation during berry development was investigated using UHPLC-MS/MS, HPLC-DAD, and SPME-GC-MS platforms. In parallel, RNA sequencing of berry transcripts was performed in order to investigate the molecular response to irrigation treatments and its relationship with metabolite accumulation. D vines suffered severe water deficit during fruit development and ripening. Severe water deficit significantly affected the phenolic accumulation in the berry; specifically increasing the concentration of caftaric and gallic acid. Water deficit accelerated the process of carotenoid degradation during berry ripening. However, D increased the concentration of zeaxanthin, the only carotenoid synthesized during berry ripening. Finally, D increased the concentration of several monoterpenes—compounds that determine the aroma of several white wines. Network analysis revealed a higher clustering of phenolic and terpenoid metabolite networks under D. Severe water deficit modulated the expression of key structural and regulatory genes that underlie the synthesis of the aforementioned metabolites in the berry. Metabolite-transcript network analysis showed that strong correlations of the level of expression of transcription factors (TFs) and structural genes with the concentration of secondary metabolites emerged under D especially for the terpenoid and phenolic pathway. Indeed, we were able to recover known TF-gene-metabolite correlations and identify novel regulatory candidates. For example, a shared regulatory network containing a MYB and a zinc-finger TF positively correlated with linalool, alpha-terpineol, nerol and many terpenoid genes. Collectively our results indicate that, in white grapes, severe water deficit affects the biosynthesis of secondary metabolites through transcriptome regulation. The observed response of berry secondary metabolism to water deficit may impact wine quality.

1 - The University of British Columbia, Wine Research Centre, 2205 East Mall, Wine Research Centre, Vancouver, BRITISH COLUMBIA, V6T 1Z4, Canada
2 - Fondazione Edmund Mach, Department of Food Quality and Nutrition, Via E. Mach 1, San Michele all'Adige, 38010, Italy
3 - Istituto di Genomica Applicata, Parco Scientifco e Tecnologico Luigi Danieli, via Jacopo Linussio 51, Udine, 33100, Italy
4 - University of Udine, Department of Agricucultural and Environmental Sciences, Via delle Scienze 208, Udine, 33100, Italy

Keywords:
Abiotic stress
Fruit
secondary metabolites
Irrigation
grapevine.

Presentation Type: Oral Paper:Papers for Topics
Session: 7
Location: Salon 13/14/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 9:15 AM
Number: 7006
Abstract ID:990
Candidate for Awards:None